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What This Guide Helps With
Troubleshoots oxygen measurement and calibration problems caused by sensor condition, gas supply, connections, setup, environment, or service-level measurement faults.
Step-by-Step Troubleshooting
1. Protect the Patient From Questionable Oxygen Delivery
Do not rely on a ventilator with an unverified oxygen reading for patient therapy. Transfer the patient to another verified ventilator or independently verified oxygen-delivery method before troubleshooting.
Expected outcome: The patient receives reliable ventilation and oxygen therapy independent of the suspect measurement.
2. Confirm the Reported Condition
Determine whether:
- Calibration will not complete
- Displayed oxygen is unexpectedly high or low
- Reading is unstable
- Reading disagrees with an external analyzer
- Problem occurs only at certain oxygen settings or supply conditions
Record any displayed message exactly.
Expected outcome: The oxygen-measurement problem is clearly characterized.
3. Verify Gas Supply
Confirm required gas connections are secure and the available oxygen source is appropriate for the ventilator's configured operating condition.
Inspect hoses and connectors for damage, incorrect connection, or looseness.
Expected outcome: The intended oxygen source is connected correctly and available. If correcting the external supply resolves the reading or calibration issue, proceed to final verification.
4. Verify Device Configuration and Operating Mode
Confirm the ventilator's gas-supply configuration and operating mode correspond to the actual installation and oxygen source.
Do not change protected configuration values without authorization or manufacturer documentation.
Expected outcome: Configuration matches the actual gas-supply setup. If correcting an approved configuration mismatch resolves the problem, perform full verification.
5. Inspect Accessible Oxygen-Sensor Components
Inspect accessible oxygen-sensor components, covers, connections, and associated external areas for contamination, moisture, damage, or poor seating where applicable.
Do not disassemble internal gas-analysis assemblies.
Expected outcome: The accessible oxygen-measurement components appear clean, properly installed, and undamaged.
6. Check Environmental Conditions
Ensure calibration is not being attempted in an abnormal environment containing unusual oxygen enrichment, strong airflow directly into a sampling area, or another condition that could invalidate the reference atmosphere.
Expected outcome: Calibration is performed under appropriate environmental and gas-supply conditions.
7. Perform the Approved Oxygen Calibration
Run the applicable oxygen-sensor calibration according to current Drager instructions.
Do not repeatedly recalibrate an obviously unstable sensor as a substitute for troubleshooting.
Expected outcome: Calibration completes without error. If it succeeds, verify measurement accuracy with approved test equipment.
8. Compare With an Independent Oxygen Analyzer
Using an approved ventilator analyzer or oxygen analyzer, compare measured delivered oxygen with the ventilator indication across appropriate test conditions.
Do not invent acceptance tolerances; use current manufacturer or organizational criteria.
Expected outcome: The ventilator oxygen indication agrees with the external reference within applicable limits. If so, troubleshooting can stop.
9. Evaluate Sensor Condition
If calibration repeatedly fails or the reading remains unstable despite verified gas supply and setup, the oxygen sensor may require replacement or service according to manufacturer guidance.
Expected outcome: A serviceable sensor produces stable readings and completes calibration. Persistent failure requires further evaluation.
10. Remove From Service if Oxygen Measurement Cannot Be Verified
Do not return a ventilator to clinical use if oxygen delivery or displayed oxygen cannot be verified with approved test equipment.
Expected outcome: The ventilator is either verified accurate or removed from service.
If the Problem Persists
External gas supply, configuration, environment, and basic sensor conditions have been ruled out. Remaining causes may involve the oxygen sensor, sensor interface, gas-mixing system, signal processing, internal pneumatics, or another service-level fault.
The ventilator should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate Drager documentation and approved gas-analysis equipment
- Repaired or calibrated only by qualified personnel
After repair, verify oxygen concentration across applicable test conditions along with ventilation and alarm performance before return to service.
Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
When oxygen measurement is questioned, verify both the displayed value and the actual delivered gas with independent test equipment.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Respiratory Therapy reported that the Savina 300 oxygen reading was unstable and oxygen calibration would not complete."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found the external oxygen connection was not fully seated, producing an inconsistent gas supply."
Resolution
What action was taken.
Example:
"The oxygen connection was secured, calibration completed successfully, and delivered oxygen was verified using an approved analyzer."
Helpful Details to Include (If Known)
- Exact calibration message
- Oxygen source used
- Gas connection condition
- Device gas-supply configuration
- Displayed oxygen value
- Independent analyzer value
- Sensor condition
- Calibration result
- Results after correction
- Final device status
Final Thought
Oxygen measurement directly affects patient safety. Verify the gas source and configuration before assuming sensor failure, confirm the final reading independently, escalate unverified oxygen performance, and document the correction clearly.
That is successful troubleshooting.